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Right!
Virgo A is a galaxy, not a star at all! We call Virgo A a radio galaxy because it emits radio waves. Radio galaxies are thought to have black holes at their centers. Charged particles, accelerated by the gravitational pull of the black hole, interact with weak magnetic fields. As they spiral around field lines at near the speed of light, radio waves are emitted. This is called synchrotron emission, and is a common emission mechanism in radio sources.
The sun emits radiation because it is hot. In addition to radio waves, the sun emits infrared, and light and shorter wavelength energy. Very little of the sun's energy output is in the radio portion of the spectrum. Although your spectrum graph of the sun shows large brightness numbers (much greater than Virgo A), this is due only to the sun's close distance. If we placed the sun as far away as the next nearest star, the amount of radio energy we would receive at our telescopes would be too small to detect.
Stars, in general, are not studied with radio telescopes.
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